01 • AP — definition & common difference d02 • AP — nth term Tn = a + ( n − 1 )d03 • AP — sum of first n terms Sn04 • AP — nth term from sums: Tn = Sn − Sn−105 • GP — definition & common ratio r06 • GP — nth term Tn = arn−107 • GP — sum of first n terms Sn08 • GP — sum to infinity S∞ = a1 − r09 • Example — 11th term of AP 5, 8, 11, …10 • Example — number of terms of AP 7, 11, …, 16311 • AP — sum of first 15 terms for −7, −2, 3, … using Sn formula12 • AP — sum of multiples of 13 between 270 and 420 (a=273, l=416)13 • AP — find n if Sn=175 for 4, 7, 10, …14 • GP — sum for sequence starting at 23, 1, 112, … , 5 11615 • GP — first three terms 6k+8, 16, 2k: find k, then Sn16 • GP — sum to infinity for 24, 12, 6, … ( r = 12 )
